When connecting two optical fib ers(FOC), there are different end face couplings: Physical Contact(PC), Super Physical Contact( SPC), Ultra Physical Contact( UPC) and Angle Polished Convex( APC). The different FOC couplings are distinguished by the polish of the FOC end faces, by the return loss( RL) and the insertion loss( IL).
Physical Contact (PC) is the simplest end face coupling. To ensure that as much light energy as possible is transferred from one optical fiber to the other, the surfaces of both optical fibers touch during Physical Contact. The end face of the optical fiber can be ground flat, as in end face coupling, or lenticular, as in lens coupling.
Coupling with physical contact has the advantage that few reflections are generated at it; on the other hand, the surface is more likely to be scratched during the mating process. Typical values for return loss are over 30 dB and for insertion loss less than 0.4 dB.